Sadly it has no effect here on what DVI-Port my display is connected...
This phenomenon is actually not specifically related to hackintoshes but to regular Mac systems as well:
http://forums.macrumors.com/showthread.php?t=778806
http://legacy.macnn.com/articles/09/08/29/....snow.leopards/
So it seems to be a "official" problem of Mac OS X 10.6(.1).
Maybe those who solved this problem by connecting the display to another DVI-Port could provide some benchmarks (before and after) to compare the results. Somehow I'm a little leery of that solution...
Greetings,
Daniel